Irregularly shaped non-spherical supported catalyst, and a process for hydroconverting heavy oil fractions

ABSTRACT

The present invention concerns a catalyst for hydrotreating and/or hydroconverting heavy metal-containing hydrocarbon feeds, said catalyst comprising a support in the form of mainly irregular and non-spherical alumina-based agglomerates the specific shape of which results from a crushing step, and containing at least one catalytic metal or a compound of a catalytic metal from group VIB and/or group VIII (groups 8, 9 and 10 of the new periodic table notation), optionally at least one doping element selected from the group constituted by phosphorus, boron and silicon (or silica which does not form part of that which may be contained in the selected support) and halogens, said catalyst essentially being constituted by a plurality of juxtaposed agglomerates each formed by a plurality of acicular platelets, the platelets of each agglomerate generally being oriented radially with respect to each other and with respect to the centre of the agglomerate. The specific shape of the catalyst improves its performance when using it for hydroconverting/hydrotreating heavy metal-containing hydrocarbon feeds. 
     The invention also concerns the use of said catalyst alone or as a mixture in a fixed bed or ebullated bed reactor.

FIELD OF THE INVENTION

The present invention concerns a catalyst for hydrotreating and/orhydroconverting heavy metal-containing hydrocarbon feeds, said catalystcomprising a support in the form of mainly irregular and non-sphericalalumina-based agglomerates the specific shape of which results from acrushing step, and comprising at least one catalytic metal or a compoundof a catalytic metal from group VIB (group 6 in the new periodic tablenotation) and/or group VIII (groups 8, 9 and 10 of the new periodictable notation), optionally at least one doping element selected fromthe group constituted by phosphorus, boron and silicon (or silica whichdoes not form part of that which may be contained in the selectedsupport) and halogens, said catalyst essentially being constituted by aplurality of juxtaposed agglomerates each formed by a plurality ofacicular platelets, the platelets of each agglomerate generally beingoriented radially with respect to each other and with respect to thecentre of the agglomerate. The specific shape of the catalyst improvesits performance when using it for hydroconverting/hydrotreating heavymetal-containing hydrocarbon feeds.

PRIOR ART

The skilled person will be aware that during hydrorefining and/orhydroconverting oil fractions containing organometallic complexes, themajority of those complexes are destroyed in the presence of hydrogen,hydrogen sulphide and a hydrotreatment catalyst. The constituent metalof those complexes then precipitates in the form of a solid sulphidewhich will become bound to the inner surface of the pores. This isparticularly the case with complexes of vanadium, nickel, iron, sodium,titanium, silicon and copper which are naturally present in crude oilsto a greater or lesser extend depending on the origin of the oil andwhich, during distillation operations, tend to become concentrated inthe high boiling point fractions and in particular in residues. This isalso the case with coal liquids which comprises metals, in particulariron and titanium. The general term “hydrodemetallization” is used todenote destruction or deaggregation of organometallic complexes inhydrocarbons.

The accumulation of solid deposits in the pores of a catalyst maycontinue until some of the pores controlling access of reagents to afraction of the interconnected pore network is plugged so that thatfraction becomes inactive even though the pores of that fraction areonly slightly obscured or even intact. That phenomenon may thus causepremature and major deactivation of the catalyst. This is particularlythe case with hydrodemetallization reactions carried out in the presenceof a supported heterogeneous catalyst. The term “heterogeneous” meansnot soluble in the hydrocarbon feed. In this case, it can be shown thatthe pores of the periphery become blocked more quickly that the centralpores. Similarly, the pore mouths become blocked more quickly than theirother parts. Pore obstruction goes hand in hand with a gradual reductionin their diameter, which increasingly limits diffusion of molecules andaccentuates the concentration gradient and thus the heterogeneity of thedeposit from the periphery to the interior of the porous particles, tothe point that total obstruction of the pores mouth to the exterioroccurs very rapidly: access to the almost intact internal porosity ofthe particles is thus impossible for the reagents and the catalyst isprematurely deactivated.

The phenomenon which has just been described is well known as pore mouthplugging. Proof of its existence and an analysis of its causes have beenwidely published in the international scientific literature.

A catalyst for hydrotreating heavy metal-containing hydrocarbon cutsmust thus be composed of a support having a pore profile, a porestructure and a shape (geometry) which is particularly suited to theintragranular diffusional constraints specific to hydrotreatments toavoid problems with plugging mentioned above.

Usually, the catalysts are in the form of beads or extrudates and arecomposed of an alumina-based support having a particular porosity and anactive phase based on mixed sulphides constituted both by a sulphide ofa group VIB metal (preferably molybdenum) and a sulphide of a group VIIImetal (preferably Ni or Co). The metals are deposited in the oxide stateand are sulphided to be active for hydrotreatment. The atomic ratiobetween the group VIII element and the group VIB element which isusually considered to be optimal, group VIII atom/group VIB atom, is inthe range 0.4 to 0.6. Recently, it has been shown in European documentEP-A1-1 364 707 (FR-A-2 839 902) that independently of the pore texture,a ratio of less than 0.4 can limit catalyst deactivation and thusprolong the service life of the catalysts.

The skilled person will be aware that two types of alumina-based supportfor catalysts for hydrorefining and/or hydroconverting heavymetal-containing hydrocarbon feeds. These supports are broadlydistinguished by their pore distribution profiles.

Catalysts with a bimodal porosity profile are highly active, but have apoorer retention capacity than catalysts with a polymodal porosityprofile.

The polymodal porosity profile corresponds to a graph of the cumulativedistribution of the pore volume as a function of the pore diameterobtained by the mercury intrusion method which is neither monomodal norbimodal, in the sense that distinct categories of pores appear with porediameters which are centred on well defined mean values do not appear,but a relatively continuous pore distribution is seen between twoextreme diameter values. Between those extreme values, there is nohorizontal stage in the pore distribution curve. Said polymodaldistribution is linked to a “thorny chestnut husk” or “sea-urchins” porestructure obtained with alumina agglomerates prepared by the rapiddehydration of hydrargillite then agglomerating the flash alumina powderobtained in accordance with one of the Applicant's patents (U.S. Pat.No. 4,552,650-IFP). The prepared alumina agglomerates may be in the formof beads or in the form of extrudates, as shown in FR-A-2 764 213 andU.S. Pat. No. 6,043,187.

The thorny chestnut husk or sea-urchins structure is constituted by aplurality of juxtaposed agglomerates each formed by a plurality ofacicular platelets, the platelets of each agglomerate generally beingradially orientated with respect to each other and with respect to thecentre of the agglomerate. At least 50% of the acicular platelets have adimension along their longer axis of between 0.05 and 5 micrometers andpreferably between 0.1 and 2 micrometers, a ratio of this dimension totheir average width of between 2 and 20, preferably between 5 and 15,and a ratio of this dimension to their average thickness of between 1and 5000, preferably between 10 and 200. At least 50% of theagglomerates of acicular platelets constitutes a collection ofpseudo-spherical particles with a mean size of between 1 and 20micrometers, preferably between 2 and 10 micrometers. A highly suitableimage which can be used to help to represent such a structure is a pileof thorny chestnut-husks or of a pile of sea-urchins, hence the porestructure denominations “thorny chestnut husk” or “sea-urchins” which isused by the skilled person.

The majority of the pores is constituted by the free spaces locatedbetween the radiating acicular platelets. These pores, which are bynature “wedge-shaped”, have a continuously variable diameter of between100 and 1000 Å. The network of interconnected macropores results fromthe space which is left free between the juxtaposed agglomerates.

These catalysts with a polymodal pore profile have a pore distribution(determined by mercury porosimetry) which is preferably characterized asfollows:

-   -   total pore volume: 0.7 to 2.0 cm³/g;    -   % of total pore volume as pores with a mean diameter of less        than 100 Å: between 0 and 10    -   % of total pore volume as pores with a mean diameter between 100        and 1000 Å: between 40 and 90    -   % of total pore volume as pores with a mean diameter between        1000 and 5000 Å: between 5 and 60    -   % of total pore volume as pores with a mean diameter between        5000 and 10000 Å: between 5 and 50    -   % of total pore volume as pores with a mean diameter of more        than 10000 Å: between 5 and 20.

The specific surface area of these catalysts, measured using the BETmethod, is in the range 50 to 250 m²/g.

The “thorny chestnut husk” or “sea-urchins” pore structure associatedwith the pore distribution characteristics described above can producehydrorefining and/or hydroconversion catalysts with very high retentionpowers while keeping the hydrodemetallization activity high, whichperformances cannot be achieved with bimodal catalysts. The reasons arethat the “wedge-shaped” shape of the mesopores in the thorny chestnuthusk or sea-urchins structure compensate for or cut out theconcentration gradients of the reagents which would normally beestablished in a cylindrical pore, which phenomenon forms a highlyfavorable geometry which can counter pore mouth plugging. Further, eachmesopore or practically each pore has access independently of others tothe interstitial macroporosity favoring homogeneous accumulation ofdeposits without premature deactivating plugging.

These catalysts, however, suffer from the disadvantage of being lessactive as regards initial activity than bimodal catalysts for HDM(hydrodemetallization), HDAC7 (hydroconverting asphaltenes which areinsoluble in n-heptane), HDCCR (hydroconverting carbonaceous residuesquantified by Conradson carbon analysis).

In processes for ebullated bed hydroconversion processing hydrocarbonfeeds with high metal contents (Ni+V of more than 250 ppm, for example),the poorer initial performances of that catalyst with a thorny chestnuthusk pore structure or sea-urchins pore structure requires a dailyfairly large quantity of fresh makeup catalyst.

For ebullated bed hydroconversion, the catalyst is used in the form ofbeads or extrudates. The “bead” form means that bed fluidization is morehomogeneous and its abrasion resistance properties are improved over the“extrudate” form. The beads move more homogeneously and the homogeneityof the solids in the bed means that a good metal retention level isachieved while avoiding the phenomena of segregation due to gravity. Thebead size is also adjustable as a function of the desired chemicalactivity to minimize problems linked to diffusion of molecules into thepores of the catalyst. Metal capture is considerably enhanced in anebullated bed compared with a fixed bed.

Similarly, in fixed bed processes for hydrorefining residues, thecatalyst with a thorny chestnut husk or sea-urchins pore structure has apoorer performance (compared with bimodal catalysts) as regards theinitial performance in the HDAC7, HDM, HDCCR functions, although theyhave a high retaining power which is necessary to process hydrocarbonfeeds with a high metals content (Ni+V of more than 40 ppm, forexample). Thus, using that type of catalyst penalizes the performance ofdownstream HDS catalysts, which are thus poorly protected fromasphaltenes, from Ni+V deposition and from coke deposition.

FR-A-2 534 828 describes the preparation of catalysts containing one ormore metals from groups V, VI and/or VIII and an alumina, silica orsilica-alumina type support, said support being crushed but when anautoclaving step is carried out in the process, the crushing operationis systematically carried out after that autoclaving step.

Surprisingly, the Applicant has discovered that polymodal catalysts witha thorny chestnut husk structure in the form of alumina-basedagglomerates, which are mainly irregular and non-spherical, may beobtained with an improved strength compared with those obtained by theprocess of FR-A-2 534 828 by modifying the position of the crushing stepin the steps of the preparation process. This important advantage allowsthe catalyst to be used in an ebullated bed reactor, whereas this wouldhave been impossible with the catalyst obtained by the process of FR-A-2534 828.

Along with the increased strength, the catalysts obtained in accordancewith the invention can produce optimum performances as regards HDAC7,HDM activity, stability and retention capacity for hydroconverting heavymetal-containing hydrocarbon feeds.

DESCRIPTION OF THE INVENTION

The invention concerns a catalyst which can be used in fixed orebullated bed hydrorefining (hydrotreatment) and/or hydroconversion ofheavy metal-containing hydrocarbon feeds having both an improvedactivity, a high retention power, a high stability of performance and ahigh strength.

Said catalyst comprises a porous alumina-based support having a thornychestnut husk or sea-urchins pore structure and is characterized by theirregular and non-spherical shape of said support. This is mainly in theform of fragments obtained by crushing alumina beads using a process asdefined below.

More precisely, the invention concerns a catalyst comprising analumina-based support, at least one catalytic metal or compound of acatalytic metal from group VIB and/or VIII, the pore structure of whichis composed of a plurality of juxtaposed agglomerates each formed by aplurality of acicular platelets, the platelets of each agglomerate beinggenerally oriented radially with respect to the others and with respectto the centre of the agglomerate, said support having an irregular andnon-spherical shape and being mainly in the form of fragments obtainedby crushing alumina beads, and prepared using a process including thefollowing steps:

-   -   a) granulation starting from an active alumina powder having a        low crystallinity and/or amorphous structure, to obtain        agglomerates in the form of beads;    -   b) maturing in a moist atmosphere between 60° C. and 100° C.        then drying said beads;    -   c) sieving to recover a fraction of said beads;    -   d) crushing said fraction;    -   e) calcining at least a portion of said crushed fraction at a        temperature in the range 250° C. to 900° C.;    -   f) impregnating with acid and hydrothermal treatment at a        temperature in the range 80° C. to 250° C.;    -   g) drying then calcining at a temperature in the range 500° C.        to 1100° C.

The granulometry of the support obtained at the end of the process issuch that the diameter of the sphere which circumscribes at least 80% byweight of said fragments after crushing is in the range 0.05 to 3 mm. Inthe case in which the catalyst is used in an ebullated bed, saiddiameter is preferably between 0.1 and 2 mm and, highly preferably,between 0.3 and 1.5 mm. In the case in which a fixed bed catalyst isused, said diameter is preferably between 1.0 and 2.0 mm.

The active phase of said catalyst contains at least one catalytic metalor a compound of a catalytic metal from group VIB (group 6 in the newperiodic table notation), preferably molybdenum or tungsten, and/oroptionally at least one catalytic metal or a compound of a catalyticmetal from group VIII (groups 8, 9 and 10 in the new periodic tablenotation), preferably nickel or cobalt. The catalyst may furthercomprise at least one doping element selected from phosphorus, boron,silicon and halogens (group VIIA or group 17 of the new periodic tablenotation), preferably phosphorus. The silicon deposited on the catalystand considered henceforth to be a doping element, is distinguished fromthe silicon which may be present in an endogenous manner in the initialsupport. The deposited silicon can be quantified using a Castaingmicroprobe.

Preferably, the catalyst contains at least one group VIB metal(preferably molybdenum) and optionally at least one non noble group VIIImetal, preferably nickel. A preferred catalyst of this type is Ni Mo P.

Without wishing to be bound by any particular theory, it appears thatthe improved properties of the catalyst of the present invention are dueto improved diffusion of species into the interior of the catalyst grainand by association, the small size of the grains or fragments, theirspecific form resulting in a higher external surface area/grain volumeratio and to a thorny chestnut husk or sea-urchins porosity.

The “wedge-shaped” shape of mesopores of the thorny chestnut husk orsea-urchins structure compensates or cuts out the reagent concentrationgradients which would normally occur in a cylindrical pore. The smallgrain size of the support and their specific irregular non-sphericalshape encourages homogeneous ingress of reagents into the macroporosityand at each facet, without plugging the pore mouths. Finally, the meanfree path or effective diameter inside a grain or fragment is alwaysless than the diameter of the sphere circumscribing said fragment, whileit is strictly identical to the diameter in the case of beads. Despitethe very irregular shape of the grains or fragments, it is possible,however, to circumscribe a sphere in each of them and the fragment sizeis defined by the diameter of the sphere circumscribing said fragment.

For an equal size, the specific shape of the grains or fragments,irregular and non-spherical, thus encourages intragranular diffusionphenomena. The hydrodemetallization (HDM) and hydroconversion functionsof asphaltenes which are insoluble in n-heptane (HDAC7) are increased.

The quantity of group VIB metal, expressed as a % by weight of oxidewith respect to the weight of the final catalyst, is in the range 1% to20%, preferably in the range 5% to 15%.

The quantity of non-noble group VIII metal, expressed as a % by weightof oxide with respect to the final catalyst weight, may be in the range0 to 10%, preferably in the range 1% to 4%.

The quantity of phosphorus, expressed as a % by weight of oxide withrespect to the final catalyst weight, may be in the range 0.3% to 10%,preferably in the range 1% to 5%, and more preferably in the range 1.2%to 4%.

The quantity of boron, expressed as a % by weight of oxide with respectto the weight of the final catalyst, is less than 6%, preferably lessthan 2%.

The atomic ratio between the elemental phosphorus and the group VIBelement is advantageously in the range 0.3 to 0.75.

When at least one doping element is silicon, the silicon content is inthe range 0.1% to 10% by weight of oxide with respect to the finalcatalyst weight.

When at least one doping element is a halogen (group VIIA), the halogencontent is less than 5% by weight with respect to the final catalystweight.

Preparation of Support

The alumina-based support has a pore structure which is composed of aplurality of juxtaposed agglomerates each formed by a plurality ofacicular platelets, the platelets of each agglomerate generally beingoriented radially with respect to the others and with respect to thecentre of the agglomerate, said support having an irregular andnon-spherical shape and being mainly in the form of fragments obtainedby crushing alumina beads, and prepared using a process including thefollowing steps:

-   -   a) granulation starting from an active alumina powder having a        low crystallinity and/or amorphous structure, to obtain        agglomerates in the form of beads;    -   b) maturing in a moist atmosphere between 60° C. and 100° C.        then drying said beads;    -   c) sieving to recover a fraction of said beads;    -   d) crushing said fraction;    -   e) calcining at least a portion of said crushed fraction at a        temperature in the range 250° C. to 900° C.;    -   f) impregnating with acid and hydrothermal treatment at a        temperature in the range 80° C. to 250° C.;    -   g) drying then calcining at a temperature in the range 500° C.        to 1100° C.

The granulometry of the support obtained at the end of the process issuch that the diameter of the sphere circumscribing at least 80% byweight of said fragments after crushing is in the range 0.05 to 3 mm. Inthe case in which the catalyst is used in an ebullated bed, saiddiameter is preferably between 0.1 and 2 mm and, highly preferably,between 0.3 and 1.5 mm. In the case in which a fixed bed catalyst isused, said diameter is preferably between 1.0 and 2.0 mm.

-   -   a) The first step, termed granulation, aims to form        substantially spherical agglomerates from an active alumina        powder having a low crystallinity and/or amorphous structure        produced using the process described in FR-A-1 438 497. That        process consists of moistening, using an aqueous solution, the        active alumina having a low crystallinity and/or amorphous        structure, then agglomerating it in a granulator or pelletizer.        Preferably, one or more pore-forming agents are added during        granulation. Particular pore-forming agents which may be used        are wood flour, wood charcoal, cellulose, starches, naphthalene        and, generally, any organic compound which may be eliminated by        calcining.        -   The term “low crystallinity alumina structure” means an            alumina wherein X ray analysis produces a diagram having no            or only a few diffuse lines corresponding to crystalline            phases of the low temperature transition aluminas and            essentially comprising khi, rho, eta, gamma, pseudo-gamma            phases and mixtures thereof. The active alumina employed is            generally obtained by rapid dehydration of aluminium            hydroxides such as bayerite, hydrargillite or gibbsite,            nordstrandite or aluminium oxyhydroxides such as boehmite or            diaspore. Said dehydration may be carried out in any            suitable apparatus using a stream of hot gas. The inlet            temperature for the gas into the apparatus generally varies            from about 400° C. to 1200° C. and the contact time for the            hydroxide or oxyhydroxide with the hot gases is generally in            the range between a fraction of a second and 4 to 5 seconds.        -   The specific surface area, measured by the BET method, of            the active alumina obtained by rapid dehydration of            hydroxides or oxyhydroxides is generally between about 50            and 400 m²/g, the particle diameter is generally in the            range 0.1 to 300 micrometres and is preferably in the range            1 to 120 micrometres. The loss on ignition, measured by            calcining at 1000° C., is generally in the range 3% to 15%,            corresponding to a H₂O/Al₂O₃ mole ratio in the range from            about 0.17 to 0.85.        -   In a particular implementation, an active alumina is used            which derives from the rapid dehydration of Bayer hydrate            (hydrargillate) which is a readily commercially available,            cheap aluminium hydroxide; such an active alumina is well            known in the art; a process for its preparation has been            described in FR-A-1 108 011.        -   The active alumina employed may be used as is or after            treatment so that its sodium content, expressed as Na₂O, is            less than 1000 ppm by weight. Further, it generally contains            between 100 and 1000 ppm by weight of endogenous silica. The            active alumina employed may or may not have been milled.    -   b) The spherical agglomerates obtained are then matured in a        moist atmosphere at low temperature, preferably in the range        from 60° C. to about 100° C., then dried at a temperature which        is generally 100° C. to 120° C.    -   c) At this stage, the agglomerates, substantially in the form of        beads, have sufficient mechanical strength to be sieved to        select the granulometric range which is suitable for the desired        final granulometry. Thus, for example, to obtain a final support        with a size range of 0.7-1.4 mm, a bead fraction in the range        1.4-2.8 mm is sieved and selected; to obtain a final support in        the 1-2 mm range size, a bead fraction with a size range of 2-4        mm is selected; finally, to obtain a final support in the size        range 2-3 mm, a bead fraction with a size range of 4-6 mm is        sieved and selected.    -   d) Next, the bead fraction with the selected size range is        crushed. This operation is carried out in any known crusher        known to the skilled person and preferably in a ball mill. It        lasts from 5 to 60 minutes, preferably 10 to 30 minutes.        -   At the end of the crushing step, the alumina support is            mainly in the form of fragments with a highly irregular and            non-spherical shape. To better define the shape obtained,            the fragments may be said to be in the form of broken beads            without having very clean break surfaces, or in the form of            solids the closest geometrical shape of which is an            irregular polyhedron not necessarily having planar faces.            The term “mainly” means that at least 50% by weight,            preferably at least 60% by weight of the spherical            agglomerates have effectively undergone a modification to            their shape during crushing, the complementary portion            representing the spherical agglomerates remaining intact. It            is well known that crushing is a low efficiency, crude            operation and routinely, a non negligible portion of the            grains is not crushed.        -   To obtain a final catalyst with sufficient mechanical            strength, the crushing step must be carried out prior to            calcining and hydrothermal treatment (steps e) and f)            respectively).    -   e) After the crushing step, at least a portion of the fragments        is calcined at a temperature in the range from about 250° C. to        about 900° C., preferably 500° C. to 850° C. The portion which        is not calcined generally corresponds to fines which do not fall        within the required dimensional range. Preferably, all of the        crushed fraction is calcined.    -   f) Acid impregnation of the support is then carried out,        followed by hydrothermal treatment using the method described in        U.S. Pat. No. 4,552,650 which may be applied in its entirety to        the present process:        -   the crushed agglomerates are treated in an aqueous medium            comprising—and preferably constituted by—a mixture of at            least one acid to dissolve at least a portion of the support            alumina, and at least one compound supplying an anion which            is capable of combining with the aluminium ions in solution,            the compound being chemically distinct from said acid;        -   simultaneously or successively treating the treated crushed            agglomerates hydrothermally (or in an autoclave). The term            “acid to dissolve at least a portion of the support alumina”            means any acid which, brought into contact with the active            alumina agglomerates defined above, dissolves at least a            portion of the aluminium ions. The acid dissolves at least            0.5% and at most 15% by weight of the alumina of the            agglomerates. Its concentration in the aqueous treatment            medium is less than 20% by weight and preferably in the            range 1% to 15%. Preferably, strong acids are used such as            nitric acid, hydrochloric acid, perchloric acid or sulphuric            acid, or weak acids such as acetic acid, used in a            concentration such that their aqueous solution has a pH of            less than about 4.        -   The term “compound supplying an anion capable of combining            with aluminium ions in solution” means any compound which is            capable in solution of liberating an anion A^(n−) which with            the Al³⁺ cations is capable of forming products in which the            atomic ratio n(A/Al) is 3 or less.            -   A particular case of these compounds may be illustrated                by basic salts with general formula Al₂(OH)_(x)A_(y) in                which 0<x<6; ny<6; n represents the number of charges on                the anion A.            -   The concentration of that compound in the aqueous                treatment medium is less than 50% by weight and                preferably in the range 3% to 30%. Preferably, compounds                capable in solution of liberating anions selected from                the group constituted by nitrate, chloride, sulphate,                perchlorate, chloroacetate, dichloroacetate,                trichloroacetate, bromoacetate, dibromoacetate anions,                and anions with general formula RCOO(—) are used, in                which R represents a radical from the group comprising                H, CH₃, C₂H₅, CH₃CH₂, (CH₃)₂CH.            -   Compounds which are capable in solution of liberating                the anion A^(n−) may carry out said liberation either                directly, for example by dissociation, or indirectly,                for example by hydrolysis. The compounds may in                particular be selected from the group comprising:                mineral or organic acids, anhydrides, organic or mineral                salts, esters. Of the mineral salts, alkali salts or                alkaline-earth salts which are soluble in aqueous media                may be cited, such as those of sodium, potassium,                magnesium or calcium, ammonium salts, aluminium salts                and salts of rare earths.            -   This first treatment may be carried out either by dry                impregnation of agglomerates or by immersing the                agglomerates in the aqueous acid solution. The term “dry                impregnation” means contact of alumina agglomerates with                a volume of solution which is less than or equal to the                total pore volume of the treated agglomerates.            -   In a particularly preferred implementation, the aqueous                medium is a mixture of nitric and acetic acid or nitric                acid and formic acid.            -   The hydrothermal treatment is carried out at a                temperature in the range from about 80° C. to about 250°                C., for a period of time in the range from about 5                minutes to about 36 hours.            -   This hydrothermal treatment causes no loss of alumina.            -   Preferably, the temperature is in the range 120° C. to                220° C. for a period in the range 15 minutes to 18                hours.            -   This treatment constitutes a hydrothermal treatment of                the active alumina agglomerates which transforms at                least a portion thereof into boehmite. This hydrothermal                treatment (autoclaving) may be carried out either under                saturated vapour pressure or at a partial vapour                pressure of water vapour of at least 70% of the                saturated vapour pressure corresponding to the treatment                temperature.            -   The association of an acid which can dissolve at least a                portion of the alumina and an anion which can form the                products described above during hydrothermal treatment                results in the production of a particular boehmite which                is a precursor for the acicular support platelets of the                invention the growth of which proceeds radially from                crystallization seeds.            -   Further, the concentration of acid and compound in the                treatment mixture and the hydrothermal treatment                conditions used are such that there is no loss of                alumina. The increase in porosity following treatment is                thus due to expansion of the agglomerates during                treatment and not to a loss of alumina.    -   g) Finally, the crushed agglomerates are optionally dried at a        temperature which is generally in the range from about 100° C.        to 200° C. for a period which is sufficient to remove water        which is not chemically bound. The agglomerates then undergo        thermal activation at a temperature in the range from about        500° C. to about 1100° C. for a period in the range from about        15 minutes to 24 hours.

The active alumina support obtained in accordance with the invention,mainly with an irregular and non-spherical shape, generally has thefollowing characteristics: the loss on ignition, measured by calciningat 1000° C., is in the range from about 1% to about 15% by weight, thespecific surface area is in the range from about 80 to about 300 m²/g,their total pore volume is in the range from about 0.45 to about 1.5cm³/g.

The resulting crushed active alumina agglomerates also preferably havethe following characteristics:

-   -   a specific surface area in the range 75 to 250 m^(2/)g;    -   a settled packing density in the range from about 0.35 to 0.80        g/cm³;    -   a total pore volume (TPV) in the range 0.5 to about 2.0 cm³/g;    -   a pore distribution, determined using the Hg porosimetry        technique, which is preferably characterized as follows:        -   % of total pore volume as pores with a mean diameter of less            than 100 Å: between 0 and 10        -   % of total pore volume as pores with a mean diameter between            100 and 1000 Å: between 40 and 90        -   % of total pore volume as pores with a mean diameter between            1000 and 5000 Å: between 5 and 60        -   % of total pore volume as pores with a mean diameter between            5000 and 10000 Å: between 5 and 50        -   % of total pore volume as pores with a mean diameter of more            than 10000 Å: between 5 and 20.

The process cited above for preparing an alumina support can modify thepore volume distribution depending on the pore size of the untreatedagglomerates. It can increase the proportion of pores in the range 100to 1000 Å, reduce the proportion of pores of less than 100 Å and reducethe proportion of pores of over 5000 Å by modifying the proportion ofpores in the range 1000 to 5000 Å less.

The alumina agglomerates obtained may have been thermally stabilized byrare earths, silica or alkaline-earth metals, as is well known to theskilled person. In particular, they may be stabilized using the processdescribed in United States patent U.S. Pat. No. 4,061,594.

Deposit of Active Phase and Doping Element or Elements onto SupportObtained

The deposit obtained at the end of step g) is impregnated with at leastone solution of at least one catalytic metal and optionally with atleast one dopant.

The deposit of active phase in the oxide state and the doping element orelements onto the crushed alumina agglomerates is preferably carried outby the “dry” impregnation method which is known to the skilled person.Impregnation is highly preferably carried out in a single step using asolution containing all of the constituent elements of the finalcatalyst (co impregnation). Other impregnation sequences may be carriedout to obtain the catalyst of the present invention.

It is also possible to introduce part of the metals and part of thedoping element or elements or even all of them during preparation of thesupport, in particular during the granulation step.

Sources of elements from group VIB which may be used are well known tothe skilled person. Examples of sources of molybdenum and tungsten whichmay advantageously be used are oxides, hydroxides, molybdic and tungsticacids and their salts, in particular ammonium salts such as ammoniummolybdate, ammonium heptamolybdate, ammonium tungstate, phosphomolybdicand phosphotungstic acids and their salts, acetylacetonates, xanthates,fluorides, chlorides, bromides, iodides, oxyfluorides, oxychlorides,oxybromides, oxyiodides, carbonyl complexes, thiomolybdates andcarboxylates. Preferably, oxides and ammonium salts are used, such asammonium molybdate, ammonium heptamolybdate or ammonium tungstate.

Sources of group VIII elements which may be used are known; examples arenitrates, sulphates, phosphates, halides, carboxylates such as acetatesor carbonates, hydroxides and oxides.

The preferred phosphorus source is orthophosphoric acid, however saltsand esters such as alkaline phosphates, ammonium phosphates, galliumphosphates or alkyl phosphates are also suitable. Phosphorous acids, forexample hypophosphorous acid, phosphomolybdic acid and its salts,phosphotungstic acid and its salts may also advantageously be used. Thephosphorus may, for example, be introduced in the form of a mixture ofphosphoric acid and a basic nitrogen-containing organic compound such asammonia, primary and secondary amines, cyclic amines, compounds from thepyridine family and quinolines and compounds from the pyrrole family.

The boron source may be boric acid, preferably orthoboric acid H₃BO₄,ammonium diborate or pentaborate, boron oxide or boric esters. The boronmay, for example be introduced using a solution of boric acid in awater/alcohol mixture or in a water/ethanolamine mixture.

A number of silicon sources may be employed. Thus, it is possible to useethyl orthosilicate Si(OEt)₄, siloxanes, silicones, halogen silicatessuch as ammonium fluorosilicate (NH₄)₂SiF₆ or sodium fluorosilicateNa₂SiF₆. Silicomolybdic acid and its salts or silicotungstic acid andits salts may also advantageously be employed. The silicon may, forexample, be added by impregnating with ethyl silicate in solution in awater/alcohol mixture.

Sources of the group VIIA element (halogens) which may be used are wellknown to the skilled person. Examples are fluoride anions which may beintroduced in the form of hydrofluoric acid or its salts. Said salts areformed with alkali metals, ammonium or an organic compound. In thelatter case, the salt is advantageously formed in the reaction mixtureby reaction between the organic compound and hydrofluoric acid. It isalso possible to use hydrolyzable compounds which may liberate fluorideanions in water, such as ammonium fluorosilicate (NH₄)₂SiF₆, silicontetrafluoride SiF₄ or sodium fluorosilicate Na₂SiF₆. The fluorine may,for example, be introduced by impregnating with an aqueous solution ofhydrofluoric acid or ammonium fluoride.

Advantageously, after said support impregnation, the process forpreparing the catalyst of the present invention comprises the followingsteps:

-   -   leaving the moist solid in a moist atmosphere at a temperature        in the range 10° C. to 80° C.;    -   drying the moist solid obtained at a temperature in the range        60° C. to 150° C.;    -   calcining the solid obtained after drying at a temperature in        the range 150° C. to 800° C.

Calcining is not necessary in the case in which the impregnationsolutions are examples of compounds containing elemental nitrogen.

Characteristics of Catalyst

The pore distribution of the catalyst, determined by mercury porosity,is as follows:

-   -   % of total pore volume as pores with a mean diameter of less        than 100 Å: between 0 and 10    -   % of total pore volume as pores with a mean diameter between 100        and 1000 Å: between 40 and 90    -   % of total pore volume as pores with a mean diameter between        1000 and 5000 Å: between 5 and 60    -   % of total pore volume as pores with a mean diameter between        5000 and 10000 Å: between 5 and 50    -   % of total pore volume as pores with a mean diameter of more        than 10000 Å: between 5 and 20.

The total pore volume of the catalysts of the invention, determined bymercury porosimetry, is in the range 0.4 to 1.8 g/cm³.

Preferably, the settled packing density of the catalysts of theinvention is in the range 0.35 to 0.80 g/cm³.

Preferably, in the catalysts of the present invention, the diameter ofthe pores at VHg/2 is in the range 300 to 700 Å, i.e. the mean porediameter wherein the volume on the pore distribution graph correspondsto half the total pore volume is in the range 300 to 700 Å, i.e. 30 to70 nm.

The catalysts of the invention have a specific surface area, measured bythe BET method, in the range 50 to 250 m²/g.

To use the catalyst of the invention in an ebullated bed, the mechanicalstrength of the catalyst is a determining factor and is measured bydetermining the percentage of fines (particles passing through a 850 μmsieve) produced when the catalyst is rotated for a given period in acylinder provided with baffles. At the end of the test, the solidobtained is sieved and the fines are weighed. The loss on attrition isquantified using the ASTM D4058-96 standard.

The loss on attrition is then calculated using the following formula:

% loss on attrition=100(1-weight of catalyst with a size of more than850 μm after test/weight of catalyst with size more than 850 μm loadedinto cylinder).

The skilled person will normally assume that a catalyst is only usablein an ebullated bed reactor when the loss on attrition measured by thismethod is less than 5% by weight.

For the catalysts of the invention, the loss on attrition quantifiedusing the ASTM D4058-96 standard is less than 5% by weight, andpreferably 2% or less.

To use the catalyst of the invention in fixed bed mode, the mechanicalstrength is determined by measuring the crush strength using the Shell(ESH) method which consists of crushing a certain quantity of particlesand recovering the fines which are generated. The crush strengthcorresponds to the force exerted to obtain a percentage of fines (finesbeing the particles passing through a 425 μm sieve) representing 0.5% ofthe mass of particles which undergo the test. The method usually used,known as the Shell Method, has the reference “Shell Method SeriesSMS1471-74” and is carried out in a bed crushing apparatus sold by VinciTechnologie under the reference “Bulk crush strength-Shell-SMS Method”.

Generally, a catalyst can be used in fixed bed mode if its Shell crushstrength is over 1.0 MPa.

For the catalysts of the invention, the crush strength measured usingthe Shell method is over 1.0 MPa and preferably 1.5 MPa or more.

The invention also concerns the process for preparing the catalystincluding the support preparation process followed by impregnating thesupport using at least one solution of at least one catalytic metal andan optional dopant.

Use of the Catalyst of the Invention inHydroconverting/Hydrocracking/Hydrotreating Hydrocarbon Feeds in anEbullated Bed

The catalysts of the invention may be employed in an ebullated bedreactor alone or partially in the form of fragments and partially in theform of beads, as described in U.S. Pat. No. 4,552,650, or in the formof cylindrical extrudates.

The feeds may, for example, be atmospheric residues or vacuum residuesfrom straight through distillation, deasphalted oils, residues fromconversion processes such as those derived from coking, or from fixedbed, ebullated bed or moving bed hydroconversion. These feeds may beused as is or diluted with a hydrocarbon fraction of a mixture ofhydrocarbon fractions which may, for example, be selected from productsfrom the FCC process, a light cycle oil (LCO), a heavy cycle oil (HCO),a decanted oil (DO), a slurry, or they may be derived from distillation,gas oil fractions, in particular those obtained by vacuum distillationdenoted VGO (vacuum gas oil). The heavy feeds may thus include cutsderived from coal liquefaction, aromatic extracts or any otherhydrocarbon cut.

The heavy feeds generally have initial boiling points of more than 300°C., more than 1% by weight of molecules having a boiling point of morethan 500° C., a Ni+V metals content of more than 1 ppm by weight, and anasphaltenes content, precipitated in heptane, of more than 0.05%.

In one implementation, part of the converted effluents may be recycledupstream of the unit operating the hydroconversion/hydrotreatmentprocess.

The heavy feeds may be mixed with powdered coal; this mixture isgenerally termed a slurry. These feeds may be by-products from theconversion of coal and re-mixed with fresh coal. The coal content in theheavy feed generally and preferably represents 0.25 by weight(coal/feed) and may vary between 0.1 and 1. The coal may containlignite, it may be a sub-bituminous coal or it may be bituminous. Anytype of coal may be used in the invention, both in the first reactor andin all of the ebullated bed reactors.

In such a process, the catalyst is generally used at a temperature inthe range 320° C. to 470° C., preferably 400° C. to 450° C., at apartial pressure of hydrogen of about 3 MPa to about 30 MPa, preferably10 to 20 MPa, at a space velocity of about 0.1 to 10 volumes of feed pervolume of catalyst per hour, and with a ratio of gaseous hydrogen toliquid hydrocarbon feed in the range 100 to 3000 normal cubic metres percubic metre, preferably 200 to 1200 normal cubic metres per cubic metre.

For residue hydroconversion, a particular application of the catalyst ofthe invention is the use of the catalyst in the presence of coal mixedwith the heavy feed to be converted. As described in patents U.S. Pat.No. 4,874,506 and U.S. Pat. No. 4,437,973, the powdered coal is mixedwith a hydrocarbon feed which is richer in hydrogen for conversion inthe presence of hydrogen and a supported catalyst. This operation isgenerally carried out in one or more reactors in series operating inebullated bed mode. Using the catalyst of the invention could improvethe hydrodynamic behaviour of the system and the continuous catalystwithdrawal unit. As an example, the conversion of coal in a liquid iscarried out by the first reactor and then the HDM, the impurities arecaptured at the same time and then a finishing step may be carried outusing other catalysts.

The catalysts of the present invention preferably undergo asulphurization treatment to transform at least part of the metallicspecies into the sulphide before bringing them into contact with thefeed to be treated. This sulphurization activation treatment is wellknown to the skilled person and may be carried out using any methodwhich has been described in the literature.

One conventional sulphurization method which is well known to theskilled person consists of heating the mixture of solids in a stream ofa mixture of hydrogen and hydrogen sulphide or in a stream of a mixtureof hydrogen and hydrocarbons containing sulphur-containing molecules ata temperature in the range 150° C. to 800° C., preferably in the range250° C. to 600° C., generally in a traversed bed reaction zone.

Process for Hydroconverting/Hydrocracking/Hydrotreating HydrocarbonFeeds in Fixed Bed Mode

The catalysts described above may also be used in a fixed bed reactor,alone or partly in the form of fragments and partly in the form of beadsas described in U.S. Pat. No. 4,552,650 or in the form of cylindricalextrudates.

The feeds may, for example, be atmospheric residues or vacuum residuesfrom direct distillation, deasphalted oils, residues from conversionprocesses such as those from coking, fixed bed, ebullated bed or movingbed hydroconversion. These feeds may be used as is or be diluted with ahydrocarbon fraction or a mixture of hydrocarbon fractions which may,for example, be selected from products derived from the FCC process, alight cycle oil (LCO), a heavy cycle oil (HCO), a decanted oil (DO), aslurry, or they may be derived from distillation, gas oil fractions, inparticular those obtained by vacuum distillation denoted VGO (vacuum gasoil). The heavy feeds may thus include cuts derived from coalliquefaction, aromatic extracts, or any other hydrocarbon cut.

The heavy feeds generally have initial boiling points of more than 300°C., more than 1% by weight of molecules having a boiling point of morethan 500° C., a Ni+V metals content of more than 1 ppm by weight, and anasphaltenes content, precipitated in heptane, of more than 0.05%.

In one implementation, part of the converted effluents may be recycledupstream of the unit operating the hydroconversion/hydrotreatmentprocess.

In such a process, the catalyst is generally used at a temperature inthe range 320° C. to 450° C., preferably 350° C. to 410° C., at apartial pressure of hydrogen of about 3 MPa to about 30 MPa, preferably10 to 20 MPa, at a space velocity of about 0.05 to 5 volumes of feed pervolume of catalyst per hour, preferably 0.2 to 0.5 volumes of feed pervolume of catalyst per hour, and with a ratio of gaseous hydrogen toliquid hydrocarbon feed in the range 200 to 5000 normal cubic metres percubic metre, preferably 500 to 1500 normal cubic metres per cubic metre.

The catalysts used in the present invention preferably undergo asulphurization treatment to transform at least part of the metallicspecies into the sulphide form before bringing them into contact withthe feed to be treated. This sulphurization activation treatment is wellknown to the skilled person and may be carried out using any methodwhich has been described in the literature.

One conventional sulphurization method which is well known to theskilled person consists of heating the mixture of solids in a stream ofa mixture of hydrogen and hydrogen sulphide or in a stream of a mixtureof hydrogen and hydrocarbons containing sulphur-containing molecules ata temperature in the range 150° C. to 800° C., preferably in the range250° C. to 600° C., generally in a traversed bed reaction zone.

The following examples illustrate the invention described herein withoutin any way limiting its scope.

EXAMPLE 1 Preparation of Crushed Alumina Agglomerates in Accordance Withthe Invention

The starting material was alumina obtained by very rapid decompositionof hydrargillite in a stream of hot air (T=1000° C.). The productobtained was constituted by a mixture of transition aluminas: (khi) and(rho) aluminas. The specific surface area of this product was 300 m²/gand the loss on ignition (LOI) was 5%.

The alumina (after milling) was in the form of a powder the meanparticle diameter of which was 7 micrometres.

This alumina was mixed with wood flour as a pore-forming agent (15% byweight) then formed in a granulator or pelletizer for a period which wasadapted to the desired granulometry. The agglomerates obtained underwenta maturation step by passing steam at 100° C. for 24 hours then drying.They were then sieved and crushed and finally calcined.

These beads were then dry impregnated with a solution containing, forexample, a mixture of nitric acid and acetic acid in an aqueous phase inan impregnator drum. Once impregnated, they were introduced into anautoclave for about 2 hours, at a temperature of 210° C. and a pressureof 20.5 bars.

At the autoclave outlet, crushed alumina agglomerates were obtained inaccordance with the invention which were dried for 4 hours at 100° C.and calcined for 2 hours at 650° C.

The agglomerate size was in the range 1 to 1.5 mm. Their pore volume was0.95 cm³/g with a multimodal pore distribution. The specific surfacearea of the support was 130 m²/g.

EXAMPLE 2 Preparation of Alumina Beads (Not in Accordance With theInvention)

A catalyst was prepared in the form of beads using the procedure ofExample 1 with the exception of the crushing step.

Beads with a granulometry in the range 1.4 to 2.8 mm were selected.

EXAMPLE 3 Preparation of Crushed Alumina Agglomerates, in Accordancewith the Invention

The support of this example was prepared as described in Example 1, butthe granulation time and the sieving-crushing steps were modified toobtain agglomerates with a size in the range 1.4 to 2.8 mm.

EXAMPLE 4 Preparation of Alumina Agglomerates (Not in Accordance Withthe Invention)

A catalyst was prepared in the form of beads using the procedure ofExample 1 with the exception of the crushing step which was carried outafter autoclaving.

At the autoclave outlet, after the drying step (4 h, 100° C.) and thecalcining step (2 h, 650° C.), the beads were crushed to obtain a1.4-2.8 mm fraction.

EXAMPLE 5 Preparation of Catalysts A, B, C and D From the Supports ofExamples 1, 2, 3, 4

We dry impregnated the supports of Examples 1, 2, 3, 4 with an aqueoussolution comprising molybdenum and nickel salts and phosphoric acid. Themolybdenum precursor was molybdenum oxide MoO₃ and the nickel precursorwas nickel carbonate Ni(CO)₃. After maturation at ambient temperature ina water-saturated atmosphere, the impregnated supports were driedovernight at 120° C. and calcined at 500° C. for 2 hours in dry air. Thefinal molybdenum trioxide content was 9.4% of the finished catalystweight. The final nickel oxide NiO content was 2% of the finishedcatalyst weight. The final phosphoric oxide P₂O₅ content was 2% of thefinished catalyst weight.

The textural and physico-chemical characteristics of catalysts A, B, Cand D derived respectively from the supports of Examples 1, 2, 3 and 4are shown in Table 1.

TABLE 1 Catalyst A B C D MoO₃ (wt %) 9.4 9.4 9.4 9.4 NiO (wt %) 2.0 2.02.0 2.0 P₂O₅ (wt %) 2.0 2.0 2.0 2.0 SiO₂ (wt %) — — — Ni/Mo (at/at) 0.400.40 0.40 0.40 P/Mo (at/at) 0.42 0.42 0.42 0.42 dMo (at/nm²) 3.8 3.8 3.83.8 SPD (g/cm³) 0.55 0.52 0.51 0.52 S_(BET) (m²/g) 97 105 103 100 TPV Hg(cm³/g) 0.80 0.95 0.90 0.90 Dp at VHg/2 (Å) 350 380 370 370 V Hg > 500 Å0.35 0.44 0.40 0.40 (cm³/g) V Hg > 1000 Å 0.26 0.30 0.28 0.28 (cm³/g)

EXAMPLE 6 Comparison of Mechanical Resistance to Attrition of CatalystsA, B, C, D for Ebullated Bed Use

The mechanical resistance to attrition of catalysts A, B, C and D wasdetermined using the method shown in the description.

Table 2 below shows the results obtained for catalysts A, B, C, D.

TABLE 2 Catalyst A B C D % fines 1.5% 2% 2% 12% produced after attrition(wt)

Thus, catalyst D could not be used in an ebullated bed as the amount offines generated at the end of the attrition test was much higher than 5%by weight.

EXAMPLE 7 Comparison of Performances in Ebullated Bed ResidueHydroconversion

The performances of catalysts A (in accordance with the invention), B(not in accordance) and C (in accordance with the invention) werecompared during a pilot test in a pilot unit comprising a tubularreactor provided with a device to maintain the catalyst inside thereactor in a permanently ebullated state. The pilot unit used wasrepresentative of an H-OIL® industrial unit for ebullated bedhydroconversion residues described in many patents, for example U.S.Pat. No. 4,521,295 and U.S. Pat. No. 4,495,060.

The pilot reactor was loaded with 1 litre of catalyst.

The unit was charged with a gas oil from vacuum distillation or VD withthe characteristics shown in Table 3.

TABLE 3 Feed VD SAFANIYA VR BOSCAN AR Spec grav 0.9414 1.0457 1.023Sulphur (weight %) 2.92 5.31 5.5 Nitrogen (ppm by 1357 4600 5800 weight)Viscosity (cSt) 13.77 5110 1380 Temp viscosity (° C.) 100 100 100Viscosity (cSt) 38.64 285 120 Temp viscosity (° C.) 70 150 150 C.Conradson (wt %) 23.95 16.9 Asphalt. C7 (wt %) 14.5 14.0 Ni (ppm byweight) <2 52 125 V (ppm by weight) 3.3 166 1290 D1160: IP, ° C. 361 496224 D1160: 05% vol, ° C. 416 536 335 D1160: 10% vol, ° C. 431 558 402D1160: 20% vol, ° C. 452 474 D1160: 30% vol, ° C. 467 523 D1160: 40%vol, ° C. 479 566 D1160: 50% vol, ° C. 493 D1160: 60% vol, ° C. 507D1160: 70% vol, ° C. 522 D1160: 80% vol, ° C. 542 D1160: 90% vol, ° C.568 D1160: 95% vol, ° C. 589 D1160: EP, ° C. 598 558 566

The temperature was increased to 343° C. then the test feed, a Safaniyatype vacuum distillation residue (VR) was injected. The reactiontemperature was than raised to 410° C. The hydrogen flow rate was 600l/l; the hourly space velocity was 0.3 l/l/h.

The conditions of the test were isothermal, which allowed thedeactivation of the catalyst to be measured by directly comparing theperformances at different ages. The ages are expressed here in m³ offeed/kg of catalyst (m³/kg), which represents the cumulative quantity offeed passed over the catalyst compared with the loaded weight ofcatalyst.

The conversion performance, HDM, is defined as follows:

Conversion (wt %)=((% wt of 550° C.+)_(feed) _(−(% wt of) 550°C.+)_(test)/((% wt of 550° C.+)_(feed)*100

HDM (wt %)=((ppm by wt of Ni+V)_(feed)−(ppm by wt of Ni+V)_(test)/(( ppmby wt of Ni+V)_(feed)*100

The feed was then changed to a Boscan atmospheric residue. This feedallowed the metal retention of the catalyst to be evaluated. The testaimed to maintain the % HDM in the range 80% to 60%. To this end, thereaction temperature was kept at 410° C. The test was stopped when theHDM fell below 60%. Conversion was maintained between 50% and 60% byweight to obtain good fuel stability. To evaluate the stability of theproducts formed, a measurement was carried out using the Shell P valuemethod on the 350° C.+ fraction of the effluent recovered after thetest.

Table 4 compares the performance of catalysts A, B and C at the start ofthe test (0.56 m³/kg) and at the end of the test (1.44 m³/kg).

Catalyst D could not be evaluated even in terms of initial activity asthe production of fines at the end of the second day of the test(age<0.17 m³/kg) caused operational problems (plugging, appearance ofpressure gradients) and the unit was stopped.

TABLE 4 Retention of Shell Catalyst + age Conv (wt %) HDM (wt %) metals(wt %) P value A at 0.56 m³/kg, 55 72 9.5 1.6 Saf VR B, at 0.56 m³/kg,54 55 8.1 1.4 Saf VR C, at 0.56 m³/kg, 54 65 8.7 1.5 Saf VR A at 1.44m³/kg, 55 80 120 1.4 Boscan AR B at 1.44 m³/kg, 56 70 100 1.2 Boscan ARC at 1.44 m³/kg, 55 78 115 1.3 Boscan AR

The HDM catalysts supported on crushed agglomerates of the invention hadimproved initial HDM properties and higher stability. Higher HDMperformances were obtained with a smaller agglomerate size.

EXAMPLE 8 Comparison of Fixed Bed Mechanical Strength of Catalysts A, B,C, D

Table 5 below shows the results obtained for fixed bed crushingmeasurements carried out using the method described for catalysts A, B,C, D.

TABLE 5 Catalyst A B C D Pressure exerted 1.8 MPa 1.7 MPa 1.7 MPa 0.8MPa for 0.5% by weight of fines

The Shell crush strength for catalyst D was not compatible with use in afixed bed residue hydroconversion unit as this value was below 1 MPa.

EXAMPLE 9 Comparison of Performances in Fixed Bed ResidueHydroconversion for Catalysts A, B and C

The performances of catalysts A (in accordance), B (not in accordance)and c (in accordance) described above were compared during a fixed bedpilot test for hydrotreating various oil residues. In the firstinstance, an atmospheric residue (AR) of Middle Eastern origin (ArabianLight) was processed followed by a Venezuelan extra heavy crudeatmospheric residue (Boscan). These two residues are characterized byhigh viscosities, high Conradson carbon numbers and high asphaltenescontents. The RA Boscan also had a very high nickel and vanadiumcontents.

The characteristics of these residues are shown in Table 6:

TABLE 6 RA Arabian Light RA Boscan 15/4 density 0.9712 1.023 Viscosityat 100° C. mm²/s 161 1380 Viscosity at 150° C. mm²/s 45 120 Sulphur wt %3.38 5.5 Nitrogen ppm 2257 5800 Nickel ppm 12 125 Vanadium ppm 41 1290Iron ppm 1 8 Carbon wt % 84.8 83.40 Hydrogen wt % 11.1 10.02 Aromaticcarbon % 24.8 29.0 Molecular mass g/mol 528 730 Conradson carbon wt %10.2 16.9 C5 asphaltenes wt % 6.4 24.1 C7 asphaltenes wt % 3.4 14.9 SARAwt % Saturates wt % 28.1 8.7 Aromatics wt % 46.9 35.0 Resins wt % 20.134.0 Asphaltenes wt % 3.5 14.6 Simulated distillation IP ° C. 296 224 5% ° C. 400 335 10% ° C. 422 402 20% ° C. 451 474 30% ° C. 474 523 40%° C. 502 566 50% ° C. 536 60% ° C. 571 70% ° C. 80% ° C. 90% 95% EP ° C.571 566

The tests were carried out in a hydrotreatment pilot unit comprising afixed bed tubular reactor. The reactor was filled with 1 litre ofcatalyst. The fluid flow (residue+hydrogen) in the reactor was upwards.This type of pilot unit is representative of the operation of one of thereactors of a HYVAHL unit from IFP for fixed bed residuehydroconversion.

After a step for sulphurization by circulating a gas oil cutsupplemented with dimethyldisulphide in a reactor at a final temperatureof 350° C., the unit was operated for 300 hours with Arabian lightatmospheric residue at 370° C., 150 bars of total pressure using a HSVof 0.5 l of feed/l of catalyst/h. The hydrogen flow rate was such thatit had a ratio of 1000 l/l of feed. The test conditions using ALAR wereisothermal, which allowed the initial deactivation of the catalyst to bemeasured by directly comparing the performances at different ages. Theages were expressed as hours of operation with Arabian light atmosphericresidue, the zero time being taken as that when the test temperature(370° C.) was reached.

The HDM, HDASC7 and HDCCR performances are defined as follows:

HDM (wt %)=((ppm by wt of Ni+V)_(feed)−(ppm by wt of Ni+V)_(test)((ppmby wt of Ni+V)_(feed)*100

HDASC7 (wt %)=((wt % of asphaltenes insoluble in n-heptane)_(feed)−(wt %of asphaltenes insoluble in n-heptane)_(test)/((wt % of asphaltenesinsoluble in n-heptane)_(feed)*100

HDCCR (wt %)=((wt % of CCR)_(feed)−(wt % of CCR)_(test)/((wt % ofCCR)_(feed)*100

Table 7 compares the HDM, HDASC7and HDCCR performances of catalysts A, Band C at the start of the test (50 hours) and at the end of the test(300 hours).

TABLE 7 Catalyst + age HDM (wt %) HDASC7 (wt %) HDCCR (wt %) A at 50hours 90 91 50 B at 50 hours 83 85 40 C at 50 hours 87 88 46 A at 300hours 85 86 44 B at 300 hours 74 75 32 C at 300 hours 83 83 39

The feed was then changed to a Boscan atmospheric residue. The testconditions were aimed at maintaining a constant HDM ratio of about 80%by weight throughout the cycle. To this end, catalyst deactivation wascompensated for by progressively increasing the reaction temperature.The test was stopped when the reaction temperature reached 420° C., atemperature which is considered to be representative of the temperatureat the end of the cycle of an industrial residue hydrorefining unit.

Table 8 compares the quantities of nickel+vanadium deriving from BoscanAR deposited on the 3 catalysts.

TABLE 8 Catalyst Ni + V deposited (% of mass of fresh catalyst) CatalystA 97 Catalyst B 85 Catalyst C 91

It appears that the HDM catalysts supported on agglomerates of theinvention produced initial performances on ALAR and retention on BARwhich were better than those for the catalyst supported on beads; thegains in performances and retention are better when the agglomerates aresmaller.

1. A catalyst comprising an alumina-based support, at least onecatalytic metal or compound of a catalytic metal from group VIB and/orVIII, the pore structure of which is composed of a plurality ofjuxtaposed agglomerates and each formed by a plurality of acicularplatelets, the platelets of each agglomerate generally being orientedradially with respect to the others and with respect to the centre ofthe agglomerate, said support having an irregular and non-sphericalshape and being mainly in the form of fragments obtained by crushingalumina beads, and prepared by a process including the following steps:a) granulation starting from an active alumina powder having a lowcrystallinity and/or amorphous structure, to obtain agglomerates in theform of beads; b) maturing said beads in a moist atmosphere between 60°C. and 100° C. then drying said beads; c) sieving resultant dried beadsto recover a fraction of said beads; d) crushing said fraction; e)calcining at least a portion of said crushed fraction at a temperaturein the range of 250° C. to 900° C.; f) impregnating resultant calcinedcrushed fraction with acid and hydrothermal treatment at a temperaturein the range of 80° C. to 250° C.; g) drying resultant acidified andhydrothermally treated fraction then calcining at a temperature in therange 500° C. to 1100° C. to obtain said support.
 2. A catalystaccording to claim 1, exhibiting a loss on attrition, quantified inaccordance with the ASTM D4058-96 standard, is less than 5% by weight.3. A catalyst according to claim 1, exhibiting a loss on attrition,quantified in accordance with the ASTM D4058-96 standard, is less than2% by weight.
 4. A catalyst according to claim 1, having a crushstrength, measured using the Shell method in accordance with standardSMS 1471-74, of at least 1.5 MPa.
 5. A catalyst according to claim 1, inwhich granulation step a) is conducted with at least one pore-formingagent.
 6. A catalyst according to claim 1, comprising at least onecatalytic metal or a compound of a catalytic metal from group VIB.
 7. Acatalyst according to 1, comprising at least one catalytic metal or acompound of a catalytic metal from group VIII (columns 8, 9 and 10 ofthe new periodic table notation).
 8. A catalyst according to claim 1,further containing at least one doping element selected from the groupconstituted by phosphorus, boron, silicon and the halogens.
 9. Acatalyst according to claim 1, wherein the support in the form offragments has a size such that the diameter of a sphere circumscribingat least 80% of said fragments is in the range of 0.05 to 3 mm.
 10. Anebullated bed comprising a catalyst according to claim 9, in which thediameter of the circumscribing sphere is in the range of 0.3 to 1.5 mm.11. A fixed bed comprising a catalyst according to claim 9, in which thediameter of the circumscribing sphere is in the range 1.0 to 2.0 mm. 12.A catalyst according to claims claim 1, in which the amount of group VIBmetal, expressed as the % by weight of oxide with respect to the finalcatalyst weight, is in the range of 1% to 20% and in which the amount ofgroup VIII metal, expressed as the % by weight of oxide with respect tothe final catalyst weight, is in the range of 0 to 10%.
 13. A catalystaccording to claim 12, in which the group VIB metal is molybdenum andthe group VIII metal is nickel.
 14. A catalyst according to claim 1,containing an amount of non noble group VIII metal in the range of 1% to4% by weight.
 15. A catalyst according to claim 1, containing a dopingelement comprising phosphorus and the amount of phosphorus, expressed asa % by weight of oxide with respect to the final catalyst weight, is inthe range of 0.3% to 10%.
 16. A catalyst according to claim 15, in whichthe amount of phosphorus is in the range of 1.2% to 4% by weight.
 17. Acatalyst according to claim 1, further containing at least one dopingelement selected from the group formed by boron, silicon and thehalogens in amounts, expressed as the % by weight of oxide with respectto the final catalyst weight, of less than 6% for boron, less than 5%for the halogens and in the range of 0.1% to 10% for silicon.
 18. Acatalyst according to claim 1, having a pore distribution, determined bythe Hg porosimetry technique, as follows: % of total pore volume aspores with a mean diameter of less than 100 Å: between 0 and 10 % oftotal pore volume as pores with a mean diameter between 100 and 1000 Å:between 40 and 90 % of total pore volume as pores with a mean diameterbetween 1000 and 5000 Å: between 5 and 60 % of total pore volume aspores with a mean diameter between 5000 and 10000 Å: between 5 and 50 %of total pore volume as pores with a mean diameter of more than 10000 Å:between 5 and
 20. 19. A catalyst according to claim 1, having a settledpacking density in the range of 0.35 to 0.80 g/cm³ and a total porevolume, determined by mercury porosimetry, in the range of 0.4 to 1.8g/cm³.
 20. A catalyst according to claim 1, having a pore diameter atVHg/2 in the range of 300 to 700 Å.
 21. A catalyst according to claim 1in which, in granulation step a), the active alumina powder is moistenedwith an aqueous solution, then resultant moistened powder isagglomerated in a granulator.
 22. A catalyst according to claim 1, inwhich in step f), the crushed fraction is impregnated with an aqueoussolution comprising at least one acid which can dissolve at least aportion of the alumina of the support, and with at least one compound,distinct from said acid, supplying an anion which is capable ofcombining with aluminium ions in solution.
 23. A catalyst according toclaim 1, further comprising impregnating the support obtained at the endof step g) with at least one solution of at least one catalytic metaland optionally at least one dopant.
 24. A catalyst according to claim23, wherein after impregnation of the support, the moist solid is leftin a moist atmosphere at a temperature in the range of 10° C. to 80° C.,the moist solid obtained is dried at a temperature in the range 60° C.to 150° C. and the solid obtained is calcined after drying at atemperature in the range 150° C. to 800° C.
 25. A process forcatalytically hydrotreating and/or hydroconverting heavymetal-containing hydrocarbon feeds the improvement wherein the catalystis according to claim
 1. 26. A process according to claim 25, in whichsaid catalyst is provided in an ebullated bed mode at a temperature inthe range of 320° C. to 470° C., at a partial pressure of hydrogen ofbetween 3 MPa and 30 MPa, at a space velocity of about 0.1 to 10 volumesof feed per volume of catalyst per hour, and with a ratio of gaseoushydrogen to liquid hydrocarbon feed in the range of 100 to 3000 normalcubic meters per cubic meter.
 27. A process according to claim 25, inwhich said catalyst is provided in an ebullated bed mode at atemperature in the range of 320° C. to 450° C., at a partial pressure ofhydrogen of between 3 MPa and 30 MPa, at a space velocity of about 0.05to 5 volumes of feed per volume of catalyst per hour, and with a ratioof gaseous hydrogen to liquid hydrocarbon feed in the range of 200 to5000 normal cubic meters per cubic meter.
 28. A process according toclaim 23, in which said catalyst is partly in the form of fragments andpartly in the form of beads or in the form of cylindrical extrudates.